Cache Optimizations

For fast response time to client requests, Directory Server caches
directory information in memory. For top performance, you can tune your suffix
entry cache settings to optimize performance. Directory Server provides
easier control of cache sizing, and once tuned, the server adheres strictly
to the cache setting.

This section describes the main features of the Directory Server
cache:

Setting thresholds on dynamic memory use

Optimizing cache memory allocation

Grouping entries for simplified management

Setting Thresholds on Dynamic Memory Use

Directory Server allows you to strictly control the use of memory
for cache purposes so that less memory is used. You specify a low and high
threshold for dynamic memory use. When this threshold is reached, Directory Server
attempts to free memory from the suffix entry caches and to keep memory use
under control. If the server reaches the high threshold, the server goes into
aggressive mode to free memory. Performance is only effected when the high
threshold is reached.

This feature provides two configurable thresholds: a soft
threshold and a hard threshold. When the soft
threshold is reached, Directory Server attempts to free memory concurrently
with other operations. When the hard threshold is reached, operations on the
cache are prevented while memory is being freed. These two thresholds are
defined by two server properties:

Optimizing Cache Memory Allocation

The size of the cache determines how the memory is allocated. For example,
if the cache is less than two Gbytes, the server uses one memory pool. If
the cache size is larger than two Gbytes, the server optimizes cache memory
allocation by using as many pools as necessary, with each pool dedicated to
a particular size.